I've been trying for months to figure out why my '93 dies at idle while I'm holding the brakes. I've lost track of most of the things I've tried with no success. (ignition tune-up, carb. cleaner, engine fogger, AAMCO diagnosis, fuel pump and filter, grounding,). My neighbor says the problem is in the keyswitch. He said if I can pull the key out while it's running it is wore out. I can pull it out when running. This doesn't sound possible. What do you think?

 

it dies when you hit the brakes?


check for a vacuum leak in the lines going to to the brake booster and maybe the internals of the brake booster is shot.


also being able to pull out the key while running isnt too good

 

Yeah, check the booster vacuum line for leaks and that it's fitting good, and you might need to replace the booster. Google on how to test your booster.

 

Let me give a better description of what's happening. This truck is an auto tranny and a good scenario would be when I'm stopped, in gear, and holding the brakes. It does the same thing if I use the parking brake. Does that knock out the brake vacuum idea?
Thanks guys.

 

have you done ANY work to it recently even if its a light bulb

Also see about cleaning your throttle body and a vacuum leak can still be the cause

 

check your vacum lines then your 02 sensors or sensor
your truck should be old enaugh to run a jumper cable on your obd1 and pull the codes by watching how many times the service engine light flashes

 

Thanks guys. Tomorrow I'll do a thorough check for vacuum leaks. This is what I tried today. I've already tried a new IAC and that didn't fix it but today I just unplugged it and it ran fine except the idle was too high. Does this thing need to be calibrated? What if I screwed it in until the idle is close and just unplugged it? Maybe my thinking is way off.

 

is it a carb or fuel injected

 

if your engine runs better with teh iac valve off that means you need to replace it some will say to clean it but replaceing it is much better
also check your tbi gasket by spraying wd40 or something around it and if it dies then its that
also i would seriously check your codes
take a wire and splic both ends a little then plug it into the a&b port on your obd1 under the dash your service engine light will flash 1 then 2 times that means your computer is working
also grab yourself a chiltons or haynes it has the codes in it and 1 flash then 3 is your o2 sensor mytruck didi alot of what yours did and i replaced alot of things before checking th o2 sensor turns oout that was it the whole time

 

fuel injected